Hercostomus flavipalpus Negrobov, Kumazawa, Tago & Sato

Negrobov, O. P., Kumazawa, T., Tago, T. & Sato, M., 2016, New species of Hercostomus Loew, 1857 (Dolichopodidae, Diptera) from Japan, Zootaxa 4158 (1), pp. 65-80 : 69-70

Hercostomus flavipalpus Negrobov, Kumazawa, Tago & Sato sp. nov.

( Figs 3 A–F, 8C)

Hercostomus sp. № 14t. Tago, 2012: 9.

Type material. HOLOTYPE Ƌ, labeled: Japan, Saitama pref., Ootaki, Chichibu City 27.viii.2011, leg. T. Tago ( OMNH) . PARATYPES: 2 Ƌ, same data as holotype (1 Ƌ OMNH, 1 Ƌ VSU) ; 1 Ƌ, Japan, Okinawa, Yonehara, Ishigaki-jima , 12.vi.1994, leg. Sato (RTM); 1 Ƌ , Japan, Hokkaido, Iwana-no-sawa, Kmitoikan, Horonobe , 18.v.– 8.vi.1993, leg. Inoue ( VSU) .

Description. Male. Head with frons with silvery-white pollinosity. Face silvery-white, without hairs, not reaching lower eye margin, middle part narrower than postpedicel width. Proboscis and palpus yellow, palpus with yellow hairs and 1 black seta. Antenna ( Fig. 3 B) black, scape and pedicel yellow below. Postpedicel slightly longer than wide, obtuse apically, with small apical incision. Stylus placed at apex of postpedicel, with short hairs. Ratio of postpedicel length to width and stylus length: 1.7: 1.4: 3.5. Postocular setae black. Thorax green with metallic tinge, with weak silvery pollinosity. Pleura metallic green, with grey-white pollinosity. Propleuron with 1 black seta below and group of black hairs above. Scutellum bare above, with 2 strong black lateral setae and small marginal hairs. Legs yellow, mid coxa mostly brown excluding apex, with black setae and hairs. Hind femur with black spot at apex. Segments of tarsi simple, not widened. Femora without long hairs below. Fore tibia without long apicoventral seta, with 1 anterodorsal and 2 short posterodorsal setae, with row of small anteroventral hairs in upper 2/3. Ratio of length of fore tibia and tarsomeres (from 1st to 5th): 4.0: 2.5: 2.0: 1.3: 0.7: 0.7. Mid femur with 1 preapical outer seta above and 2–3 small preapical inner hairs. Mid tibia with 2 long and 1 short anterodorsal setae at base, 2 posterodorsal and 1 anteroventral setae. Tarsomere 1 of mid tarsus with 2 short ventral setae. Ratio of length of mid tibia and tarsomeres (from 1st to 5th): 6.6: 3.6: 2.8: 1.7: 0.9: 0.6. Hind coxa with 1 black outer seta. Hind femur with 1 preapical outer seta. Hind tibia with 2 long anterodorsal, 4 dorsal and 2–3 short anteroventral setae. Ratio of length of hind tibia and tarsomeres (from 1st to 5th): 4.2: 1.8: 3.8: 1.7: 0.9: 0.8. Tarsomeres 1–3 of hind tarsus with small anteroventral setae. Wing darkened. Costal vein without thickening at tip of R1. Ratio of costal section between R2+3 and R 4+5 to that between R4+5 and M1+2—1.8: 0.8. R4+5 and M1+2 convergent apically. Ratio of m-cu to apical part of M3+4—1.4: 2.1. Anal angle obtuse. Calypter yellow with black cilia. Halter yellow. Abdomen metallic green, with purple stripes on edges of tergites, with black setae and hairs, with silvery pollinosity laterally. Segment 8 black, covered by short black hairs. Epandrium ( Figs 3 A, D) black, oval, longer than wide. Surstylus ( Fig. 3 A) brown. Cercus ( Fig. 3 F) yellow with darkened apex, with black hairs, shorter than surstylus. Female. Unknown. Length (mm): body: 2.2–2, wing: 2.2–2.3.

Etymology. The species is named for the yellowish palpus.

Remarks. According to Stackelberg (1934) the new species is included in the third group of Hercostomus (femora yellow, postocular setae black). In the key to Palaearctic species (Selivanova et al. 2012), the new species runs to Hercostomus congruens Becker, 1922 , which is known from the Palaearctic and Oriental regions and belongs to the genus Gymnopternus . The new species can be distinguished from G. congruens (Becker, 1922) by the following features: the latter species has a cluster of fine setulae in front of the posterior spiracle and R4+5 and M1+2 are parallel distally. In the key to Chinese species ( Yang et al. 2011), the new species runs to Hercostomus wudangshanus Yang, 1997 and can be distinguished from the latter by the morphology of hypopygium and the following characters:

- Antennae black. Stylus dorsal. Postpedicel without apical incision. Hind femur yellow.... Hercostomus wudangshanus Yang - Scape and pedicel yellow below. Stylus placed near apex of postpedicel. Postpedicel with incision. Hind femur with black spot at apex................................................................... Hercostomus flavipalpus sp. nov.

Figures

FIGURE 3. Hercostomus flavipalpus sp. nov. (A) hypopygium, left lateral view; (B) antenna, lateral view; (C) basal part of apicoventral postgonite, lateral view; (D) hypopygium, ventral view; (E) ventral lobes of hypopygium; (F) cerci, dorsal view.